There are a variety of subunits, in oncornaviral RNAs, the major one of which is the 35S subunit. There are also two to four primer 4S RNAs for each 70S parent molecule. There are about 10 to the seventh power Daltons of nucleotides per virion and possibly one third of these represent genetic information. The genetic information is incorporated into the host genome in a number of steps the first of which most likely involves viral reverse transcriptase, although the other enzymes and proteins, some cellular, are probably also involved. This proposal is concerned with factors relating to the retrieval of information from the viral RNA. This involves learning the mechanism of reverse transcription which in turn requires a knowledge of the RNA structure. These are in fact two problems but because of their intimate relationship they will be dealt with as one. One major objective of this proposal is to carry out a detailed kinetic study of the reverse transcription of AMV RNA using the holo enzyme as well as its alpha subunit. A second major objective is to dissect the secondary structure of viral RNAs since we feel that it is not only important but essential to the eventual understanding of the in vivo process of information transfer. BIBLIOGRAPHIC REFERENCE: Cavalieri, L. F. and Yamaura, I. E. coli tRNAs as Inhibitors of Viral Reverse Transcription in vitro. Nucleic Acids Research 2: 2315 (1975).